res_query.c revision 1.1.1.4
1 /* $NetBSD: res_query.c,v 1.1.1.4 2009/04/12 16:35:48 christos Exp $ */ 2 3 /* 4 * Portions Copyright (C) 2004, 2005, 2008 Internet Systems Consortium, Inc. ("ISC") 5 * Portions Copyright (C) 1996-2001, 2003 Internet Software Consortium. 6 * 7 * Permission to use, copy, modify, and/or distribute this software for any 8 * purpose with or without fee is hereby granted, provided that the above 9 * copyright notice and this permission notice appear in all copies. 10 * 11 * THE SOFTWARE IS PROVIDED "AS IS" AND ISC DISCLAIMS ALL WARRANTIES WITH 12 * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY 13 * AND FITNESS. IN NO EVENT SHALL ISC BE LIABLE FOR ANY SPECIAL, DIRECT, 14 * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM 15 * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE 16 * OR OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR 17 * PERFORMANCE OF THIS SOFTWARE. 18 */ 19 20 /* 21 * Copyright (c) 1988, 1993 22 * The Regents of the University of California. All rights reserved. 23 * 24 * Redistribution and use in source and binary forms, with or without 25 * modification, are permitted provided that the following conditions 26 * are met: 27 * 1. Redistributions of source code must retain the above copyright 28 * notice, this list of conditions and the following disclaimer. 29 * 2. Redistributions in binary form must reproduce the above copyright 30 * notice, this list of conditions and the following disclaimer in the 31 * documentation and/or other materials provided with the distribution. 32 * 3. All advertising materials mentioning features or use of this software 33 * must display the following acknowledgement: 34 * This product includes software developed by the University of 35 * California, Berkeley and its contributors. 36 * 4. Neither the name of the University nor the names of its contributors 37 * may be used to endorse or promote products derived from this software 38 * without specific prior written permission. 39 * 40 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 41 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 42 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 43 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 44 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 45 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 46 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 47 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 48 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 49 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 50 * SUCH DAMAGE. 51 */ 52 53 /* 54 * Portions Copyright (c) 1993 by Digital Equipment Corporation. 55 * 56 * Permission to use, copy, modify, and distribute this software for any 57 * purpose with or without fee is hereby granted, provided that the above 58 * copyright notice and this permission notice appear in all copies, and that 59 * the name of Digital Equipment Corporation not be used in advertising or 60 * publicity pertaining to distribution of the document or software without 61 * specific, written prior permission. 62 * 63 * THE SOFTWARE IS PROVIDED "AS IS" AND DIGITAL EQUIPMENT CORP. DISCLAIMS ALL 64 * WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING ALL IMPLIED WARRANTIES 65 * OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL DIGITAL EQUIPMENT 66 * CORPORATION BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL 67 * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR 68 * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS 69 * ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS 70 * SOFTWARE. 71 */ 72 73 #if defined(LIBC_SCCS) && !defined(lint) 74 static const char sccsid[] = "@(#)res_query.c 8.1 (Berkeley) 6/4/93"; 75 static const char rcsid[] = "Id: res_query.c,v 1.11 2008/11/14 02:36:51 marka Exp"; 76 #endif /* LIBC_SCCS and not lint */ 77 78 #include "port_before.h" 79 #include <sys/types.h> 80 #include <sys/param.h> 81 #include <netinet/in.h> 82 #include <arpa/inet.h> 83 #include <arpa/nameser.h> 84 #include <ctype.h> 85 #include <errno.h> 86 #include <netdb.h> 87 #include <resolv.h> 88 #include <stdio.h> 89 #include <stdlib.h> 90 #include <string.h> 91 #include "port_after.h" 92 93 /* Options. Leave them on. */ 94 #define DEBUG 95 96 #if PACKETSZ > 1024 97 #define MAXPACKET PACKETSZ 98 #else 99 #define MAXPACKET 1024 100 #endif 101 102 /*% 103 * Formulate a normal query, send, and await answer. 104 * Returned answer is placed in supplied buffer "answer". 105 * Perform preliminary check of answer, returning success only 106 * if no error is indicated and the answer count is nonzero. 107 * Return the size of the response on success, -1 on error. 108 * Error number is left in H_ERRNO. 109 * 110 * Caller must parse answer and determine whether it answers the question. 111 */ 112 int 113 res_nquery(res_state statp, 114 const char *name, /*%< domain name */ 115 int class, int type, /*%< class and type of query */ 116 u_char *answer, /*%< buffer to put answer */ 117 int anslen) /*%< size of answer buffer */ 118 { 119 u_char buf[MAXPACKET]; 120 HEADER *hp = (HEADER *) answer; 121 u_int oflags; 122 u_char *rdata; 123 int n; 124 125 oflags = statp->_flags; 126 127 again: 128 hp->rcode = NOERROR; /*%< default */ 129 #ifdef DEBUG 130 if (statp->options & RES_DEBUG) 131 printf(";; res_query(%s, %d, %d)\n", name, class, type); 132 #endif 133 134 n = res_nmkquery(statp, QUERY, name, class, type, NULL, 0, NULL, 135 buf, sizeof(buf)); 136 #ifdef RES_USE_EDNS0 137 if (n > 0 && (statp->_flags & RES_F_EDNS0ERR) == 0 && 138 (statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC|RES_NSID))) { 139 n = res_nopt(statp, n, buf, sizeof(buf), anslen); 140 rdata = &buf[n]; 141 if (n > 0 && (statp->options & RES_NSID) != 0U) { 142 n = res_nopt_rdata(statp, n, buf, sizeof(buf), rdata, 143 NS_OPT_NSID, 0, NULL); 144 } 145 } 146 #endif 147 if (n <= 0) { 148 #ifdef DEBUG 149 if (statp->options & RES_DEBUG) 150 printf(";; res_query: mkquery failed\n"); 151 #endif 152 RES_SET_H_ERRNO(statp, NO_RECOVERY); 153 return (n); 154 } 155 156 n = res_nsend(statp, buf, n, answer, anslen); 157 if (n < 0) { 158 #ifdef RES_USE_EDNS0 159 /* if the query choked with EDNS0, retry without EDNS0 */ 160 if ((statp->options & (RES_USE_EDNS0|RES_USE_DNSSEC)) != 0U && 161 ((oflags ^ statp->_flags) & RES_F_EDNS0ERR) != 0) { 162 statp->_flags |= RES_F_EDNS0ERR; 163 if (statp->options & RES_DEBUG) 164 printf(";; res_nquery: retry without EDNS0\n"); 165 goto again; 166 } 167 #endif 168 #ifdef DEBUG 169 if (statp->options & RES_DEBUG) 170 printf(";; res_query: send error\n"); 171 #endif 172 RES_SET_H_ERRNO(statp, TRY_AGAIN); 173 return (n); 174 } 175 176 if (hp->rcode != NOERROR || ntohs(hp->ancount) == 0) { 177 #ifdef DEBUG 178 if (statp->options & RES_DEBUG) 179 printf(";; rcode = (%s), counts = an:%d ns:%d ar:%d\n", 180 p_rcode(hp->rcode), 181 ntohs(hp->ancount), 182 ntohs(hp->nscount), 183 ntohs(hp->arcount)); 184 #endif 185 switch (hp->rcode) { 186 case NXDOMAIN: 187 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); 188 break; 189 case SERVFAIL: 190 RES_SET_H_ERRNO(statp, TRY_AGAIN); 191 break; 192 case NOERROR: 193 RES_SET_H_ERRNO(statp, NO_DATA); 194 break; 195 case FORMERR: 196 case NOTIMP: 197 case REFUSED: 198 default: 199 RES_SET_H_ERRNO(statp, NO_RECOVERY); 200 break; 201 } 202 return (-1); 203 } 204 return (n); 205 } 206 207 /*% 208 * Formulate a normal query, send, and retrieve answer in supplied buffer. 209 * Return the size of the response on success, -1 on error. 210 * If enabled, implement search rules until answer or unrecoverable failure 211 * is detected. Error code, if any, is left in H_ERRNO. 212 */ 213 int 214 res_nsearch(res_state statp, 215 const char *name, /*%< domain name */ 216 int class, int type, /*%< class and type of query */ 217 u_char *answer, /*%< buffer to put answer */ 218 int anslen) /*%< size of answer */ 219 { 220 const char *cp, * const *domain; 221 HEADER *hp = (HEADER *) answer; 222 char tmp[NS_MAXDNAME]; 223 u_int dots; 224 int trailing_dot, ret, saved_herrno; 225 int got_nodata = 0, got_servfail = 0, root_on_list = 0; 226 int tried_as_is = 0; 227 int searched = 0; 228 229 errno = 0; 230 RES_SET_H_ERRNO(statp, HOST_NOT_FOUND); /*%< True if we never query. */ 231 dots = 0; 232 for (cp = name; *cp != '\0'; cp++) 233 dots += (*cp == '.'); 234 trailing_dot = 0; 235 if (cp > name && *--cp == '.') 236 trailing_dot++; 237 238 /* If there aren't any dots, it could be a user-level alias. */ 239 if (!dots && (cp = res_hostalias(statp, name, tmp, sizeof tmp))!= NULL) 240 return (res_nquery(statp, cp, class, type, answer, anslen)); 241 242 /* 243 * If there are enough dots in the name, let's just give it a 244 * try 'as is'. The threshold can be set with the "ndots" option. 245 * Also, query 'as is', if there is a trailing dot in the name. 246 */ 247 saved_herrno = -1; 248 if (dots >= statp->ndots || trailing_dot) { 249 ret = res_nquerydomain(statp, name, NULL, class, type, 250 answer, anslen); 251 if (ret > 0 || trailing_dot) 252 return (ret); 253 saved_herrno = statp->res_h_errno; 254 tried_as_is++; 255 } 256 257 /* 258 * We do at least one level of search if 259 * - there is no dot and RES_DEFNAME is set, or 260 * - there is at least one dot, there is no trailing dot, 261 * and RES_DNSRCH is set. 262 */ 263 if ((!dots && (statp->options & RES_DEFNAMES) != 0U) || 264 (dots && !trailing_dot && (statp->options & RES_DNSRCH) != 0U)) { 265 int done = 0; 266 267 for (domain = (const char * const *)statp->dnsrch; 268 *domain && !done; 269 domain++) { 270 searched = 1; 271 272 if (domain[0][0] == '\0' || 273 (domain[0][0] == '.' && domain[0][1] == '\0')) 274 root_on_list++; 275 276 ret = res_nquerydomain(statp, name, *domain, 277 class, type, 278 answer, anslen); 279 if (ret > 0) 280 return (ret); 281 282 /* 283 * If no server present, give up. 284 * If name isn't found in this domain, 285 * keep trying higher domains in the search list 286 * (if that's enabled). 287 * On a NO_DATA error, keep trying, otherwise 288 * a wildcard entry of another type could keep us 289 * from finding this entry higher in the domain. 290 * If we get some other error (negative answer or 291 * server failure), then stop searching up, 292 * but try the input name below in case it's 293 * fully-qualified. 294 */ 295 if (errno == ECONNREFUSED) { 296 RES_SET_H_ERRNO(statp, TRY_AGAIN); 297 return (-1); 298 } 299 300 switch (statp->res_h_errno) { 301 case NO_DATA: 302 got_nodata++; 303 /* FALLTHROUGH */ 304 case HOST_NOT_FOUND: 305 /* keep trying */ 306 break; 307 case TRY_AGAIN: 308 if (hp->rcode == SERVFAIL) { 309 /* try next search element, if any */ 310 got_servfail++; 311 break; 312 } 313 /* FALLTHROUGH */ 314 default: 315 /* anything else implies that we're done */ 316 done++; 317 } 318 319 /* if we got here for some reason other than DNSRCH, 320 * we only wanted one iteration of the loop, so stop. 321 */ 322 if ((statp->options & RES_DNSRCH) == 0U) 323 done++; 324 } 325 } 326 327 /* 328 * If the query has not already been tried as is then try it 329 * unless RES_NOTLDQUERY is set and there were no dots. 330 */ 331 if ((dots || !searched || (statp->options & RES_NOTLDQUERY) == 0U) && 332 !(tried_as_is || root_on_list)) { 333 ret = res_nquerydomain(statp, name, NULL, class, type, 334 answer, anslen); 335 if (ret > 0) 336 return (ret); 337 } 338 339 /* if we got here, we didn't satisfy the search. 340 * if we did an initial full query, return that query's H_ERRNO 341 * (note that we wouldn't be here if that query had succeeded). 342 * else if we ever got a nodata, send that back as the reason. 343 * else send back meaningless H_ERRNO, that being the one from 344 * the last DNSRCH we did. 345 */ 346 if (saved_herrno != -1) 347 RES_SET_H_ERRNO(statp, saved_herrno); 348 else if (got_nodata) 349 RES_SET_H_ERRNO(statp, NO_DATA); 350 else if (got_servfail) 351 RES_SET_H_ERRNO(statp, TRY_AGAIN); 352 return (-1); 353 } 354 355 /*% 356 * Perform a call on res_query on the concatenation of name and domain, 357 * removing a trailing dot from name if domain is NULL. 358 */ 359 int 360 res_nquerydomain(res_state statp, 361 const char *name, 362 const char *domain, 363 int class, int type, /*%< class and type of query */ 364 u_char *answer, /*%< buffer to put answer */ 365 int anslen) /*%< size of answer */ 366 { 367 char nbuf[MAXDNAME]; 368 const char *longname = nbuf; 369 int n, d; 370 371 #ifdef DEBUG 372 if (statp->options & RES_DEBUG) 373 printf(";; res_nquerydomain(%s, %s, %d, %d)\n", 374 name, domain?domain:"<Nil>", class, type); 375 #endif 376 if (domain == NULL) { 377 /* 378 * Check for trailing '.'; 379 * copy without '.' if present. 380 */ 381 n = strlen(name); 382 if (n >= MAXDNAME) { 383 RES_SET_H_ERRNO(statp, NO_RECOVERY); 384 return (-1); 385 } 386 n--; 387 if (n >= 0 && name[n] == '.') { 388 strncpy(nbuf, name, n); 389 nbuf[n] = '\0'; 390 } else 391 longname = name; 392 } else { 393 n = strlen(name); 394 d = strlen(domain); 395 if (n + d + 1 >= MAXDNAME) { 396 RES_SET_H_ERRNO(statp, NO_RECOVERY); 397 return (-1); 398 } 399 sprintf(nbuf, "%s.%s", name, domain); 400 } 401 return (res_nquery(statp, longname, class, type, answer, anslen)); 402 } 403 404 const char * 405 res_hostalias(const res_state statp, const char *name, char *dst, size_t siz) { 406 char *file, *cp1, *cp2; 407 char buf[BUFSIZ]; 408 FILE *fp; 409 410 if (statp->options & RES_NOALIASES) 411 return (NULL); 412 file = getenv("HOSTALIASES"); 413 if (file == NULL || (fp = fopen(file, "r")) == NULL) 414 return (NULL); 415 setbuf(fp, NULL); 416 buf[sizeof(buf) - 1] = '\0'; 417 while (fgets(buf, sizeof(buf), fp)) { 418 for (cp1 = buf; *cp1 && !isspace((unsigned char)*cp1); ++cp1) 419 ; 420 if (!*cp1) 421 break; 422 *cp1 = '\0'; 423 if (ns_samename(buf, name) == 1) { 424 while (isspace((unsigned char)*++cp1)) 425 ; 426 if (!*cp1) 427 break; 428 for (cp2 = cp1 + 1; *cp2 && 429 !isspace((unsigned char)*cp2); ++cp2) 430 ; 431 *cp2 = '\0'; 432 strncpy(dst, cp1, siz - 1); 433 dst[siz - 1] = '\0'; 434 fclose(fp); 435 return (dst); 436 } 437 } 438 fclose(fp); 439 return (NULL); 440 } 441 442 /*! \file */ 443
Indexes created Mon Sep 29 21:09:56 GMT 2025